As an information display device substitutable for liquid crystal display (LCD), information display devices with the use of technology such as an electrophoresis method, an electro-chromic method, a thermal method, dichroic-particles-rotary method have been proposed.
These conventional techniques are considered to be useful for inexpensive visual display devices of the next generation compared with a LCD due to merits such as wider field of vision close to normal printed matter, smaller power consumption or a memory function, and expected to be spread out to information displays for portable devices, electronic paper and the like. Recently, electrophoresis method for microencapsulating dispersion liquid made up with dispersion particles and coloration solution and disposing the liquid between opposed substrates, is proposed and expected.
However, in the electrophoresis method, there is a problem that a response rate is slow by the reason of viscosity resistance because the particles migrate among the electrophoresis solution. Further, there is a problem of lacking imaging repetition stability, because particles with high specific gravity of titanium oxide is scattered within solution of low specific gravity and it is difficult to maintain a stability of dispersion state. Even in the case of microencapsulating, the cell size is diminished to a microcapsule level in order to make it hard to show the above-mentioned drawbacks, however, an essential problem is not overcome at all.
Besides the electrophoresis method using behavior in the solution, recently, a method that electro-conductive particles and a charge transport layer are installed in a part of the substrate without using solution has been proposed. [The Imaging Society of Japan “Japan Hardcopy '99” (Jul. 21-23, 1999) Transaction Pages 249-252] However, the structure becomes complicated because the charge transport layer and further a charge generation layer are to be arranged. In addition, it is difficult to constantly charge the electro-conductive particles, and thus there is a drawback on the lack of stability.
As one method for overcoming the various problems mentioned above, an information display device comprising an information display panel is known, wherein the display media (particles or liquid powders) are sealed between a front substrate provided with a front electrode and a back substrate provided with a back electrode, and wherein the display media, to which an electrostatic field is applied, are made to move by means of Coulomb's force so as to display information such as an image or the like.
(Objects of the First to Third Inventions)
A drive circuit used to drive an information display panel in an information display device by passive matrix drive or dynamic drive is required to have a drive integrated circuit enable to output polarity drive voltages respectively to the row and column and a drive integrated circuit enable to output multi-valued drive voltages respectively to the row and column. However such a drive integrated circuit having a function of outputting more than one kind of voltages costs high so as to cause an increase in cost.
In addition, it is possible to use a drive integrated circuit with high withstand voltage instead of a drive integrated circuit having a function of outputting polarity drive voltages. However such a drive integrated circuit with high withstand voltage costs high so as to cause an increase in cost.
(Objects of the Forth and Fifth Inventions)
FIG. 10 is a block diagram showing an example of a method for driving a conventional information display device. In the example shown in FIG. 10, in a display panel 51 panel driving voltage is applied to a terminal 52 of the row direction by a row driver 61 while panel driving voltage is applied to a terminal 53 of the column direction by a column driver 71. The output stage of the row driver 61 has CMOS structure with two FETs 62-1 and 62-2, while the output stage of the column driver 71 has CMOS structure with two FETs 72-2 and 72-2.
In the conventional display panel 51 shown in FIG. 10, every time display image is changed, panel driving voltage is scanned along the row direction to rewrite information of an image or the like. When display image is not changed, as shown in FIG. 10 two FETs 62-1 and 62-2 of the row driver 61 and two FETs 72-1 and 72-2 of the column driver 71 are kept open state in power-off state. Therefore, the terminal 52 of the row direction and the terminal 53 of the column direction are all OPEN (high impedance) state to stay ready to next rewriting.
The above-mentioned information display device having display memory property usually does not rewrite (scan) the information until the display information is changed (although there are some other ways to rewrite the information by regular refresh of the information). In this case, if the information is distorted by electrostatic discharge etc, the defect state would be kept for a long time even though the defect is recovered by the next refresh (scan) of the display information. In addition, many of the information display devices selling ultra low power consumption have display memory function and is high impedance, therefore, the information such as image etc is easily distorted by tiny energy such as electrostatic discharge etc.